In XenForo 2.1 there seems to have a been minor code change.
XF 2.0 - Line 7 in node_list_category
Code:
<div class="block-desc">{$node.description|raw}</div></xf:if>
XF 2.1
Code:
<xf:if is="{$node.description}"><span class="block-desc">{$node.description|raw}</span></xf:if>